1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a method in a Wireless Intelligent Network (WIN) of handling subscriber services when a serving Mobile Switching Center (MSC) does not support all WIN triggers.
2. Description of Related Art
In Wireless Intelligent Networks, services are triggered by various triggering events. The triggers are independent of the services they supportxe2x80x94one trigger may be used for many services. Therefore, a service cannot be definitely ascertained from a trigger. When a subscriber signs up for WIN services, his subscriber profile in his Home Location Register (HLR) is supplied with the WIN triggers required to support his services. Thus, the HLR knows that the subscriber has WIN services, but does not know the specific services to which he subscribes.
A problem arises when a WIN subscriber roams into an MSC (or is reached from a Roamer Port on an MSC) that does not support WIN triggers (or at least one of the WIN triggers contained in the subscriber profile in the HLR). In some cases, such as when the subscriber has a non-essential service (for example, the WIN Abbreviated Dialing service), it may be desirable to allow the subscriber to xe2x80x9cfall backxe2x80x9d to a more basic set of capabilities, rather than to deny access, so that the subscriber can continue to place and receive calls. Some subscribers, however, may subscribe to services which are deemed essential, such as a prepaid service. WIN Prepaid is a service in which a prepaid account is set up, and the account is then debited for the charges for each call made to or from the Prepaid subscriber. The subscriber""s serving MSC must support the WIN Prepaid service in order for the prepaid account to be properly debited. In such cases, therefore, it may be preferable to bar the subscriber from placing or receiving calls since all calls to and from that subscriber would circumvent the Prepaid account debiting system.
Neither the MSC nor the HLR have the information required to distinguish between these two types of cases, and the published WIN standard, IS-771, does not address the issue clearly. The standard states that the HLR should not send triggers to an MSC that does not support them, but it does not state whether the MSC should allow other services that are supported, or deny access in this case. Additionally, IS-771 does not indicate what behavior is expected of the HLR when an MSC that does not support all WIN triggers sends a query to the HLR (for example, a Location Request) that would normally require the HLR to respond with a Trigger Address List.
Proposed versions of the standard suggest that the HLR should determine whether the MSC supports a set of triggers that are critical to delivering WIN service in the serving system. If so, then the Trigger Address List should be sent to the MSC. If not, the standard merely states that the HLR should consider restricting originations and terminations. There is no definition of xe2x80x9ccriticalxe2x80x9d triggers nor any suggestion of expected MSC behavior. This approach implies that the HLR should infer the services based on the triggers, but as noted above, a service cannot be definitely ascertained from a trigger since one trigger may be used for many services.
Thus, there is no existing or proposed solution to the problems encountered when a WIN subscriber roams into an MSC that does not support all WIN triggers.
In one aspect, the present invention is a method in a Wireless Intelligent Network (WIN) of handling subscriber services when a serving Mobile Switching Center (MSC) does not support all WIN triggers. The WIN includes a Home Location Register (HLR) having a subscriber profile that indicates the WIN triggers required to support a particular subscriber""s active WIN services. The method includes the steps of sending from the MSC to the HLR, an indication of the WIN triggers supported by the MSC; identifying by the HLR, the WIN triggers in the profile that are not supported by the MSC; and identifying for each WIN trigger in the profile that is not supported by the MSC, an associated service-providing entity in the network. The HLR then queries each identified service-providing entity for call-treatment instructions which are then sent from the service-providing entities to the HLR. This is followed by the steps of determining by the HLR, a call-treatment response; and sending the call-treatment response to the MSC.
Each service-providing entity may determine whether its associated unsupported service is an essential service, may prepare call-treatment instructions to allow a reduced set of services upon determining that its associated unsupported service is not an essential service, or may prepare call-treatment instructions to deny service upon determining that its associated unsupported service is an essential service.
In another aspect, the present invention is a method in a WIN of handling subscriber services when the serving MSC does not support a particular WIN trigger (Trigger X) which supports a plurality of WIN services. The HLR includes a database that associates WIN triggers with Service Control Points (SCPs), and a first SCP (SCP1) includes a Service Interaction Manager (SM) for Trigger X. The method includes the steps of sending from the MSC to the HLR, an indication that the MSC does not support Trigger X. The HLR identifies SCP1 as the SCP associated with Trigger X, and queries SCP1 for call-treatment instructions. SCP1 then identifies an SCP associated with each of the plurality of WIN services supported by Trigger X, and queries each identified SCP for call-treatment instructions related to each SCP""s associated WIN service. Each SCP then sends call-treatment instructions to SCP1 which determines a call-treatment response. The call-treatment response is then sent from SCP1 to the HLR, and from the HLR to the MSC.
In yet another aspect, the method of the present invention may be performed entirely within the HLR. The method includes the steps of receiving in the HLR, an indication of the WIN triggers supported by the MSC; identifying by the HLR, the WIN triggers in the subscriber profile that are not supported by the MSC; and identifying by the HLR, a service-providing entity in the network associated with each WIN trigger in the profile that is not supported by the MSC. The HLR then queries each identified service-providing entity for call-treatment instructions. When call-treatment instructions are received in the HLR from the service-providing entities, the HLR determines a call-treatment response, and sends the call-treatment response to the MSC.
In an alternative embodiment, the method of the present invention begins by populating a database in the HLR with a plurality of call-treatment responses. Each of the responses is associated with a different set of WIN triggers, and is determined prior to receiving from one of the MSCs in the network, an indication of the set of WIN triggers that are supported by the MSC. When an invoke message is received in the HLR with an indication of the set of WIN triggers that are supported by the MSC, the HLR identifies a call-treatment response associated with the set of WIN triggers that are supported by the MSC, and sends the call-treatment response to the MSC.